ellipse

[ ih-lips ]

noun

, Geometry.

1. a plane curve such that the sums of the distances of each point in its periphery from two fixed points, the foci, are equal. It is a conic section formed by the intersection of a right circular cone by a plane that cuts the axis and the surface of the cone. Typical equation: ( x 2 / a 2 ) + ( y 2 / b 2 ) = 1. If a = b the ellipse is a circle.

ellipse

/ ɪˈlɪps /

noun

1. a closed conic section shaped like a flattened circle and formed by an inclined plane that does not cut the base of the cone. Standard equation x ²/ a ² + y ²/ b ² = 1, where 2 a and 2 b are the lengths of the major and minor axes. Area: π ab

ellipse

/ ĭ-lĭps′ /

1. A closed, symmetric curve shaped like an oval, which can be formed by intersecting a cone with a plane that is not parallel or perpendicular to the cone's base. The sum of the distances of any point on an ellipse from two fixed points (called the foci) remains constant no matter where the point is on the curve.

ellipse

1. In geometry , a curve traced out by a point that is required to move so that the sum of its distances from two fixed points (called foci) remains constant. If the foci are identical with each other, the ellipse is a circle; if the two foci are distinct from each other, the ellipse looks like a squashed or elongated circle.

Notes

The orbits of the planets and of many comets are ellipses.

Word History and Origins

Origin of ellipse¹

First recorded in 1745–55; from French, from Latin ellīpsis ellipsis; or by back formation from the plural ellipses

Word History and Origins

Origin of ellipse¹

C18: back formation from ellipsis

Example Sentences

“The central space is simply a regular ellipse, and the walls that surround it are vertical,” he would later recall.

From New York Times

The moon doesn’t orbit Earth in a circle, however, but in an ellipse.

From Scientific American

The capsule’s drop area in Utah is an ellipse that measures 36 by 8.5 miles.

From Scientific American

It’s almost a circle, with a small but significant deviation from Euclidean perfection that actually makes Earth’s orbit a slightly squashed oval—that is, an ellipse.

From Scientific American

On Jan. 6, 2021, Trump was still president, and he urged his supporters at his rally on the ellipse to march to the Capitol and stop Congress’ ratification of Joe Biden’s victory.

From Seattle Times

Related Words

• arc
• arch
• contour
• loop
• trajectory